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Thread: Any reason TF100 (K1000) PH would be off?

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    Any reason TF100 (K1000) PH would be off?

    Had my pool water tested by our local pool store, along side a couple strip tests because I suspected the PH level shown by my TF100 kit was off (I'm adding a lot of Alkalinity increaser each week).
    TF100 (K1000) shows around 7.3, the store and strips measured 6.8 consistently (3 measurements each). There must be something else going on that I don't understand - could have a lot to do with TA being too low all the time (50-60). The TF100 kit is new. Pool temps cycle from 85 to 90F each day.

    Any thoughts?

    I ordered a self-calibrating PH tester (HI 98127) along with a 7.01 calibration solution for my Chemlink PH probe in the hope that I can have a strong frame of reference when I need it.
    38K Gallons IG, Intelliflow VS-SVRS, 30GPM 24/7, 72sqft DE Filter, Spectralight UV, Jandy C1900 driving Liquid Chlorine and Acid (toys, I know..), Jandy LXi gas heater, Aquacal SQ175 Heatpump, Riverflow Competition swimmer, Jandy automation, Touch and iAqualink, Pebblesheen | The Build

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    Re: Any reason TF100 (K1000) PH would be off?

    I would believe a drop based test result over that of a strip any day. But, if you are one of those who may have difficulty differentiating color shades, then that can cause differences. Even drop size from static electricity on the dropper can affect test outcomes.

    pH is pH and it really doesn't matter what the TA is when taking a pH reading. The TA only affects how quickly the pH changes when other chems are introduced into the water.

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    Re: Any reason TF100 (K1000) PH would be off?

    Quote Originally Posted by 257WbyMag
    I would believe a drop based test result over that of a strip any day. But, if you are one of those who may have difficulty differentiating color shades, then that can cause differences. Even drop size from static electricity on the dropper can affect test outcomes.

    pH is pH and it really doesn't matter what the TA is when taking a pH reading. The TA only affects how quickly the pH changes when other chems are introduced into the water.
    The K1000 is a nice setup for comparing shades. Even the pool store guy agreed that it was reading about 7.3. Crazy that these things are so sensitive. There is a huge difference between 6.8 and 7.3.
    38K Gallons IG, Intelliflow VS-SVRS, 30GPM 24/7, 72sqft DE Filter, Spectralight UV, Jandy C1900 driving Liquid Chlorine and Acid (toys, I know..), Jandy LXi gas heater, Aquacal SQ175 Heatpump, Riverflow Competition swimmer, Jandy automation, Touch and iAqualink, Pebblesheen | The Build

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    Re: Any reason TF100 (K1000) PH would be off?

    As long as the FC level is below 10, the PH test in the TF100 is the best PH test available at a reasonable price. I would trust it over any other PH test short of a calibrated meter. Some of the electronic testers are better if properly calibrated, but calibration tends to drift if calibration is not repeated regularly.

    The PH test reagent can go bad, though usually that takes several years. It can go bad much more quickly if it was frozen, left in the sun for several days, or stored in a very hot place (perhaps a garden shed that gets a lot of sunlight). Usually when the PH reagent goes bad it will stain the plastic bottle it comes in.

    Regardless of the test results, there clearly is something else going on. The only things that normally reduce alkalinity are acid, trichlor, and dichlor. If you need to constantly raise TA, you must be using one of those chemicals all the time. Or perhaps there is a leak and refilling the pool constantly is lowering TA? If you are using trichlor, that makes sense. But either constant acid use or a leak indicates that something is out of balance or needs to be repaired.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Any reason TF100 (K1000) PH would be off?

    Quote Originally Posted by JasonLion
    As long as the FC level is below 10, the PH test in the TF100 is the best PH test available at a reasonable price. I would trust it over any other PH test short of a calibrated meter. Some of the electronic testers are better if properly calibrated, but calibration tends to drift if calibration is not repeated regularly.

    The PH test reagent can go bad, though usually that takes several years. It can go bad much more quickly if it was frozen, left in the sun for several days, or stored in a very hot place (perhaps a garden shed that gets a lot of sunlight). Usually when the PH reagent goes bad it will stain the plastic bottle it comes in.

    Regardless of the test results, there clearly is something else going on. The only things that normally reduce alkalinity are acid, trichlor, and dichlor. If you need to constantly raise TA, you must be using one of those chemicals all the time. Or perhaps there is a leak and refilling the pool constantly is lowering TA? If you are using trichlor, that makes sense. But either constant acid use or a leak indicates that something is out of balance or needs to be repaired.
    Could it be that running a lower PH that I was expecting and the constant aeration from our water feature be pushing TA down? If the PH is more like 6.8-7.0 rather than the 7.3-7.5 I thought it was, wouldn't that cause TA to drop?

    Other readings: CYA=50, Hardness=275, Dissolved Solids=900, FC&TC=2.0
    Chemicals: Sodium Bicarbonate, Clorox 6%, Muriatic Acid
    38K Gallons IG, Intelliflow VS-SVRS, 30GPM 24/7, 72sqft DE Filter, Spectralight UV, Jandy C1900 driving Liquid Chlorine and Acid (toys, I know..), Jandy LXi gas heater, Aquacal SQ175 Heatpump, Riverflow Competition swimmer, Jandy automation, Touch and iAqualink, Pebblesheen | The Build

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    Re: Any reason TF100 (K1000) PH would be off?

    If the PH is indeed being maintained down around 7.0 with an acid feed system, that would cause dramatic acid usage and constantly falling TA. Even trying to keep PH at 7.3-7.4 in a system with aeration requires a fair bit of acid and constantly raising the TA. The lower the PH you are trying to maintain, the lower TA needs to be for the chemistry to be stable. But you really can't lower TA below about 60 without borates, or 40 with borates, which makes maintaining low PH inherently unstable. This is why we recommend keeping PH around 7.5 to 7.8. PH at 7.7 is reasonably stable in most pools with achievable TA levels.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Any reason TF100 (K1000) PH would be off?

    Alright - false alarm I guess.

    Pool Store:
    1) The pool store gave me a very different reading 2 days later. (7.8 vs. the 6.8 2 days earlier). Insane...clearly one of the two guys measuring have no idea how to run their testing setup.

    Upgraded my ability to measure PH (more sources)
    2) I bought a 7.01 PH buffer to calibrate my PH sensor
    3) I bought a general purpose PH reader that has a 2 point calibration with 7.0 and 4.0 solutions

    Now, my PH sensor, the general purpose reader, and my reagent based tester are all agreeing on the PH level - which means things were fine before the pool store confused me. I've increased my set point to 7.6, up from 7.4. I'll see how TA holds.
    38K Gallons IG, Intelliflow VS-SVRS, 30GPM 24/7, 72sqft DE Filter, Spectralight UV, Jandy C1900 driving Liquid Chlorine and Acid (toys, I know..), Jandy LXi gas heater, Aquacal SQ175 Heatpump, Riverflow Competition swimmer, Jandy automation, Touch and iAqualink, Pebblesheen | The Build

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    Re: Any reason TF100 (K1000) PH would be off?

    This thread brings up, once more, an important point to remember about BBB. Trust your own testing. Pool stores don't give the attention to detail you will give to your own pool.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Any reason TF100 (K1000) PH would be off?

    Quote Originally Posted by shakenbake
    Alright - false alarm I guess.

    Pool Store:
    1) The pool store gave me a very different reading 2 days later. (7.8 vs. the 6.8 2 days earlier). Insane...clearly one of the two guys measuring have no idea how to run their testing setup.

    Upgraded my ability to measure PH (more sources)
    2) I bought a 7.01 PH buffer to calibrate my PH sensor
    3) I bought a general purpose PH reader that has a 2 point calibration with 7.0 and 4.0 solutions

    Now, my PH sensor, the general purpose reader, and my reagent based tester are all agreeing on the PH level - which means things were fine before the pool store confused me. I've increased my set point to 7.6, up from 7.4. I'll see how TA holds.
    The Pool Store was wrong? I am stunned. No, not really.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Any reason TF100 (K1000) PH would be off?

    Quote Originally Posted by shakenbake
    - which means things were fine before the pool store confused me.
    Happens all the time.

    Stay out of pool stores.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

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    Re: Any reason TF100 (K1000) PH would be off?

    Seems like they would sell a lot of chemicals if their testing process produced random results....
    38K Gallons IG, Intelliflow VS-SVRS, 30GPM 24/7, 72sqft DE Filter, Spectralight UV, Jandy C1900 driving Liquid Chlorine and Acid (toys, I know..), Jandy LXi gas heater, Aquacal SQ175 Heatpump, Riverflow Competition swimmer, Jandy automation, Touch and iAqualink, Pebblesheen | The Build

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    Re: Any reason TF100 (K1000) PH would be off?

    They do sell a lot of chemicals, usually because the customer on the other side of the counter gets lost in the mumbo jumbo as they don't understand what they are being told. Here at TFP, we can provide you with that knowledge so that you can tell, on your own, what the problem is and what you need to do about it. 99 and 44/100 percent of the time, it doesn't require hundreds of dollars or even a trip to the pool store to make right.

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